This is a really hard question to answer with the absence of any hard data from UAL and participating carriers/unions. I wont let that stop me from trying though!

Based on data collected by a buddy of mine that was compared to our union's data (the accuracy of which depends on Aviate participants actually emailing results to the union), XJT has approximately 65-70 successful Aviate participants TOTAL in 1st and 2nd waves. Assuming each carrier has a similar pass rate, their should be around 130-140 more successful participants from the other 3 participating carriers based on comparison of their # of pilots to XJT. That equates to 195-210 participants from 1st 2 waves. From what I have heard, it seems the 1st 2 deciles of the FIFO list are CPP participants who have yet to transition. That leaves the 195-210 Aviate participants occupying deciles 3-10. That means approximately 24-26 people per decile. If(and it's a HUGE if) these #s are accurate, then the following would be a general idea of what # you are in FIFO list:
Dec 1: 1-25 CPP
Dec 2: 26-50 CPP
Dec 3: 51-75
Dec 4: 76-100
Dec 5: 101-125
Dec 6: 126-150
Dec 7: 151-175
Dec 8: 176-200
Dec 9: 201-225
Dec 10: 226-250

Look, I know these #s are wrong but by how much is the question. The margin of error is large and if we share some data we can narrow it down. I don't represent the XJT union in any capacity and definitely do not stand by the accuracy of these #s. Maybe we can all get some dialogue going to share what we do know(which isn't much).